New research links bad diet to loss of smell

A new study from Florida State University neuroscientists says so, and it has researchers taking a closer look at how our diets could impact a whole range of human functions that were not traditionally considered when examining the impact of obesity.

"This opens up a lot of possibilities for obesity research," said Florida State University post-doctoral researcher Nicolas Thiebaud, who led the study examining how high-fat foods impacted smell.

Thiebaud led the study in the lab of Biological Science Professor Debra Ann Fadool. Their work is published in the Journal of Neuroscience and shows that a high-fat diet is linked to major structural and functional changes in the olfactory system, which gives us our sense of smell.

It was the first time researchers had been able to demonstrate a solid link between a bad diet and a loss of smell.

The research was conducted over a six-month period where mice were given a high-fat daily diet, while also being taught to associate between a particular odor and a reward (water).

Mice that were fed the high-fat diets were slower to learn the association than the control population. And when researchers introduced a new odor to monitor their adjustment, the mice with the high-fat diets could not rapidly adapt, demonstrating reduced smell capabilities.

"Moreover, when high-fat-reared mice were placed on a diet of control chow during which they returned to normal body weight and blood chemistry, mice still had reduced olfactory capacities," Fadool said. "Mice exposed to high-fat diets only had 50 percent of the neurons that could operate to encode odor signals."

For Thiebaud and his colleagues, the results are opening up a whole new line of research. They will begin looking at whether exercise could slow down a high-fat diet's impact on smell and whether a high-sugar diet would also yield the same negative results on smell as a high-fat diet.

Funded by the National Institutes of Health (NIH), the study comes at an important time with obesity rates at all-time highs throughout the world. According to the NIH, more than two in three adults in the United States are considered to be overweight or obese. Additionally, about one-third of children and adolescents ages 6 to 19 are considered to be overweight or obese.